<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>表单验证的常见属性</title>
</head>

<body>
<form>
	<input type="submit" />
    required<input required placeholder="必填项." /><br />
    pattern<input pattern="[0-9][A-Z]{3}" placeholder="一个数字和三个大写字母."/><br />
    step=10<input type="number" step="10" /><br />
</form>
</body>
</html>
